This invention relates to spring assemblies for mattresses, cushions and other bedding or seating products.
A known form of pocketed spring assembly comprises a plurality of parallel strings of springs joined together either by gluing, clipping or otherwise securing the strings of springs to each other. Each string of springs comprises a strip of fabric wrapped around a plurality of coil springs which are aligned in a row. The coil springs may be part of a continuous band of coil springs made of one piece of wire such as disclosed in assignee""s U.S. Pat. No. 5,127,635, or alternatively may be individual coil springs such as disclosed in U.S. Pat. No. 4,854,023.
The strings of springs may extend longitudinally or transversely depending on the desired application.
Once a plurality of strings of springs are secured together so as to create a spring assembly, a pair of generally rectangular border wires may be connected to the spring assembly around the periphery thereof. Padding is placed over the spring assembly and the padding and spring assembly encased in an upholstered material as is conventional.
In order to create such a string of springs, a plurality of coil springs are aligned in a row and a strip of fabric is wrapped around the aligned row of coil springs so as to create two plies, one on either side of the row of springs. The edges of the strip of fabric are joined together with a longitudinal line of attachment extending longitudinally along the row of springs. The outermost edges of the strip of fabric are joined together with outermost transverse lines of attachment in order to prevent the outermost springs from falling out of the strip of fabric. Between adjacent coil springs transverse lines of attachment extend generally parallel the axis of the coil springs, separating the strip of fabric into individual pockets, each pocket containing a coil spring, such as is disclosed in assignee""s U.S. patent application Ser. No. 09/307,501.
In assignee""s U.S. Pat. No. 5,127,635, a pair of coil springs are located within each pocket rather than each pocket containing a coil spring. In this arrangement a transverse line of attachment exists between every other spring rather than between adjacent springs.
Rather than placing foam or other cushioning or padding materials on top of the upper surface of a spring assembly as is conventional, spring assemblies have been constructed utilizing strings of springs in which the cushioning or padding material is built into the string of springs.
U.S. Pat. No. 3,160,894 discloses a plurality of strings of springs joined to a wooden base. Each string of springs has a strip of padding material comprising foam or other similar material placed on top of the upper end turns of a row of springs, the strip of padding material and springs being encased in fabric. In this patent, the coil springs within each string are not located within individual pockets separated from one another. Rather, the coil springs are stapled to a base in order to keep the coil springs in place.
Similarly, French Patent No. 657648 discloses a product comprising a plurality of strings of springs placed inside compartments of fabric, each string of springs comprising a plurality of individual coil springs separated by dividers of fabric. A strip of padding material is located above the string of coil springs and inserted into one of the compartments above the string of springs.
Although these two patents do disclose continuous strips of padding incorporated into or used with a string of springs, the springs are not individually pocketed as in applicant""s invention. Furthermore, these strings of springs lack a strip of fabric surrounding a row of springs, opposite plies of the strip of fabric being secured together so as to separate the springs.
Therefore, it has been one objective of the present invention to provide a bedding or seating product with improved responsiveness to a load placed on the product.
It has further been an objective of the present invention to provide a bedding or seating product which contains cushioning material within each pocket.
It has further been an objective of the present invention to provide a bedding or seating product which does not require large amounts of cushioning or padding material to be placed on top of the bedding or seating product once the spring assembly is complete.
The pocketed bedding or seating product of the present invention which accomplishes these objectives comprises a plurality of parallel strings of individually pocketed coil springs. Adjacent strings of springs are joined to each other using conventional methods such as gluing, ultrasonic welding, or using conventional fasteners such as hog rings. The assembly of parallel strings of springs may then be joined to upper and lower generally rectangular border wires located in the top and bottom planes of the bedding or seating product. In order to complete the bedding or seating product of the present invention, a covering pad may be placed over the spring assembly and an upholstered covering placed around the covering pad and the spring assembly.
Each string of springs comprises a row of individual coil springs, a strip of fabric surrounding the coil springs and a plurality of cushioning pads placed on top of the coil springs inside the fabric. The strip of fabric is divided into a plurality of pockets by spaced transverse lines of attachment, each pocket containing one of the coil springs and at least one cushioning pad located above the coil spring. An additional cushioning pad or pads may be located below the coil spring within the pocket.
Each coil spring has an upper end turn, a lower end turn and a plurality of convolutions between the end turns defining a spring axis. Although this application illustrates and describes individual coil springs incorporated into the string of springs, it is within the contemplation of the present invention to use continuous bands of springs, each band being made of one piece of wire such as those disclosed in U.S. Pat. No. 5,127,635.
In one preferred embodiment of the present invention, a first cushioning pad is located within each pocket and is secured to the upper end turn of the coil spring within the pocket. In an alternative preferred embodiment of the present invention, a first cushioning pad is secured to the upper end turn of the coil spring within each pocket and a second cushioning pad is secured to the lower end turn of the same coil spring within the pocket, thus each pocket contains two cushioning pads located above and below the end turns of the coil spring.
In forming a string of springs, once a strip of fabric has been wrapped around a row of aligned coil springs, the longitudinal edges of the strip of fabric are joined together with a longitudinal line of attachment in any known manner, such as sewing, welding or gluing. Opposed plies of the strip of fabric on opposite sides of the coil springs are joined together between the coil springs with transverse lines of attachment, which similarly may be ultrasonic welds, sewing lines, glue lines or any other means of attaching the plies to each other.
Each pocket contains at least one cushioning pad. Each cushioning pad comprises at least one piece of foam. The cushioning pad is illustrated and described as being a piece of urethane foam sandwiched between two pieces of cloth, one of the pieces of cloth being glued or otherwise secured to the end turn of the coil spring. However, it is within the contemplation of the present invention that the cushioning pad comprise multiple pieces of foam. In addition to foam, other materials such as cotton may be used to form the cushioning pad.
By securing at least one cushioning pad to the spring within each individual pocket, each coil spring functions independently, resulting in a more comfortable bedding or seating product than heretofore known pocketed products.